Devices are described, for instance, in German Patent No. DE 197 31 420. It describes such a device, in which a temperature sensor and a pressure sensor that is fastened, to the greatest extent in a stress-free manner, on a carrier together with an evaluation circuit, are situated in a common housing. The device described is distinguished by the fact that a very precise pressure measurement is made possible, while its production is very simple. This is achieved by having the housing include at least two chambers that are separate from each other. One of these chambers is connected to the intake manifold via a connecting piece and is sealed from the environment, so that a pressure chamber is developed in which the pressure sensor is situated.
In such devices, in order to record the pressure and the temperature, one normally makes a temperature measurement via a passive component that forms the temperature sensor, that is, for example, a negative temperature coefficient resistor or NTC resistor. The passive component is connected via a wiring harness directly to an evaluation circuit, which may be provided in a control unit. The evaluation of the signal of the temperature sensor is not carried out in the common housing. Because of this wiring configuration, noise suppression is the task of the evaluation circuit.
If an increased electromagnetic load occurs with respect to irradiation onto the connection between temperature sensor and evaluation circuit, that is, the wiring harness, or onto the sensor, this may have the effect of influencing the signal of the temperature sensor. This cannot be detected by the evaluation circuit, so that the signal is regarded as a valid signal of the temperature sensor, in spite of the error that is present. It follows that additional variables, based on the signal of the temperature sensor, or rather the temperature, are influenced negatively.